This invention relates to a sewing machine with a creasing apparatus for separating and pressing two edges of two sheets of material to make an open seam, which is used in one process of the production of a pair of trousers, a jacket or the like.
Devices of this type are disclosed in U.S. Pat. Nos. 4,495,879 and in 3,934,525.
As shown in FIG. 12, these apparatuses sew together upper and lower cloths 1 and 2, separate and fold apart both edges 1a and 2a of the cloths 1 and 2, and make creases 3 along the folds. These creases 3 have been made by pressing with an iron, an electric heated puller, or the like. Use of the electric heater results in significant inefficiency, because it requires a long time to heat up the iron before starting, and also to cool down after finishing. Further, during operation, an operator might accidentally be burned by the heated iron. Moreover, it is difficult to modulate the temperature of the electric iron in response to the sewing speed of the sewing machine, in order to keep heat received by the unit length of the cloths constant irrespective of the sewing speed.